On Tue, 2015-02-10 at 13:47 -0600, Denis Kenzior wrote:
> Can you tell me why this is needed?  This sounds like abuse of 
> hashmap_foreach and an alternate data structure might be in order.

One should not be able to crash the library by (mis)using the provided
API. The implementation needs to work all the time or politely tell that
the API function call did not complete at this time.

> > So foreach logic is changed so that if user tries to remove
> > an entry from the hash while inside foreach callback, the
> > entry is not yet removed from hash but marked as removable.
> > After foreach has finished calling the callback function,
> > it checks what elements it needs to remove from the hash.
> >
> 
> So let me politely say: "No way are we doing this" ;)

Then the only alternative is to return false for any functionality that
otherwise causes the implementation to crash. For example when
inserting/removing items from the hash while an foreach is ongoing.

glib also crashed with this pattern. Or usually worked ok, as the
removed/added item wasn't always the item used in foreach or the next
item. Fixing this to allow any API call successfully work at any time
requires quite some more work to be done, the above patch by Jukka was
approximately the minimum needed for a remove to work at any one time. 

With that the insert part is still left, but it might be easier if the
one and only foreach iterator next element is remembered by the hash
data structure and the insert/remove operation move the next position
when needed. In addition, also the foreach operation needs to guard
against itself...


Cheers,

	Patrik